Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!crdgw1!ge-dab!speedway!potter From: potter@speedway.DAB.GE.COM (Jeff Potter) Newsgroups: comp.sys.atari.8bit Subject: Re: 80 columns and baud rate Summary: because Keywords: why? Message-ID: <1991Apr8.124746.25790@ge-dab.GE.COM> Date: 8 Apr 91 12:47:46 GMT References: Sender: news@ge-dab.GE.COM (USENET News System) Reply-To: potter@ge-dab.ge.com (Jeff Potter) Organization: GE Simulation & Control Systems Dept., Daytona Beach, FL Lines: 22 Nntp-Posting-Host: speedway-gw.dab.ge.com Hello again, Ray! Regarding your questions about 80 columns, baud rate, and the graphics 0 and 8 screens: The graphics 0 screen uses just as many pixels as the graphics 8 screen (40 columns by 24 rows, each character being 8x8 pixels = 320 x 192). The big difference is that graphics 0 is a character mode. This means the OS only has to write to an array of 960 bytes (40 x 24), and Antic will display this as 61,440 pixels. Each byte is used to address the character set RAM (remember all those routines to redefine the character set in old magazine articles?), which contains the 8x8 pixel definition. In graphics 8, however, there are only 8 pixels per byte, and thus 7680 bytes (61,440/8) must be manipulated per screen. Because this is eight times as much memory to be manipulated, the terminal program will run eight times slower (1200 vs. 9600) (I don't believe how nicely that worked out). Jeff -- Jeff Potter ...potter@ge-dab.ge.com ...uunet!ge-dab.GE.COM!potter ...uunet!sunny.dab.ge.com!potter